This study aims at predicting the Standard Precipitation Index (SPI) drought class transitions in Portugal, considering the influence of the North Atlantic Oscillation (NAO) as one of the main large-scale atmospheric drivers of precipitation and drought fields across the Western European and Mediterranean areas. Log-linear modeling of the drought class transition probabilities on three temporal...

Drought is a complex hazard, and it has an impact on agricultural, ecological, and socio-economic systems. The vegetation condition index (VCI), which is derived from remote-sensing data, has been widely used for drought monitoring. However, VCI based on the normalized difference vegetation index (NDVI) does not perform well in certain circumstances. In this study, we examined the utility of th...

the normalized difference vegetation index (ndvi) derived from the spot 4 satellite has been widely used to monitor moisture-related vegetation condition. the relationship between vegetation and climate index, however, is complex and has not been adequately studied with satellite sensor data. to better understand this relationship, an analysis was conducted on time series of monthly ndvi (1999–...

The Standardized Precipitation Index (SPI) has been recognized as the standard index that should be used for quantifying and reporting meteorological drought. This study aims to present application of two-dimensional correlation method determining spatial temporal variability drought among SPI series. Heatmaps were a new way visualizing series which enables visual inspection dry wet periods. de...

drought indices are commonly used to quantify and assess drought characteristics. the standardized precipitation index (spi), and recently introduced standardized precipitation-evapotranspiration index (spei) are considered as universal meteorological drought indices which allow comparisons of drought conditions across different climate regions. the spi captures anomalies in precipitation, wher...

drought is a climatic phenomenon that causes much detrimental influence on ecological environments. this research investigates the performance of meteorological drought indices in different time scales in thetajan basin in iran. indices undergone in this study include: percent normal precipitation index (pnpi), z-score index (zsi), standard precipitation index (spi), china z index (czi), modifi...

abstract precipitation is an important variable which is used in definition of drought. based on precipitation amounts, some indices are devised for drought monitoring including, the standardized precipitation index (spi) and the standard index of annual precipitation (siap). each of these drought indices are classified into some classes so that each class descripts a given severity of drought....